## Calculating % recombination and Mapping distance

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### Calculating % recombination and Mapping distance

Hey,

Im confused on how to caluclate the percent recombination and the the mapping distznce in map units. Heres my problem:

Consider a cross in Neurospora involving two allelles at the same locus,C and c. The following tetrad patterns were observed

CCcc 55

ccCC 40

CcCc 7

cCcC 3

CccC 4

cCCc 5

What is the percent recombination and the approximate distance between the genetic locus and the centromere is?

I can't calcualte my percent recombination because im unsure jof the significant difference. But I clacuated my mapping distance by: Getting the sum of all my numbers which is 114,then I added the 4 smaller numbers and I got 19. Now for my calcualteions

19/114=0.166 then divide by 2 since its two genotpyes that are CC and cc.

which equals 0.083,then I multiply by 100 which give me 8.33 mapp units.

But How do I find my percent recombination from my data?

Are there seperate equations for percent recombination and the mapping distance?

Thank you ttyl

Im confused on how to caluclate the percent recombination and the the mapping distznce in map units. Heres my problem:

Consider a cross in Neurospora involving two allelles at the same locus,C and c. The following tetrad patterns were observed

CCcc 55

ccCC 40

CcCc 7

cCcC 3

CccC 4

cCCc 5

What is the percent recombination and the approximate distance between the genetic locus and the centromere is?

I can't calcualte my percent recombination because im unsure jof the significant difference. But I clacuated my mapping distance by: Getting the sum of all my numbers which is 114,then I added the 4 smaller numbers and I got 19. Now for my calcualteions

19/114=0.166 then divide by 2 since its two genotpyes that are CC and cc.

which equals 0.083,then I multiply by 100 which give me 8.33 mapp units.

But How do I find my percent recombination from my data?

Are there seperate equations for percent recombination and the mapping distance?

Thank you ttyl

Your reasoning is not correct though (unless I misunderstood you). You said “19/114=0.166 then divide by 2 since its two genotypes that are CC and cc.”

0.166… or 16.6% is frequency of crossover during meiosis, but only ½ of the product is recombinant. That is why you have to divide by 2; RF = 1/2 of the frequency of crossover during meiosis in this case.

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